Hydraulic control circuit of vehicular power transmission apparatus

Abstract

A hydraulic control circuit of a vehicular power transmission apparatus includes: a first passageway providing communication between a pump and a strainer; a second passageway providing communication between the pump and a feeding passageway; a third passageway interconnecting the first passageway and the second passageway; a first check valve being disposed between the strainer and a connecting point between the first passageway and the third passageway, and allowing the oil to flow from a strainer side to a pump side; a second check valve being disposed between the feeding passageway and a connecting point between the second passageway and the third passageway, and allowing the oil to flow from the second passageway to a feeding passageway side; and a third check valve being disposed in the third passageway, and allowing the oil to flow from the first passageway to a second passageway side.

1 . A hydraulic control circuit of a vehicular power transmission apparatus, comprising:
 an oil pump that draws an operating oil through a first port and discharges the operating oil through a second port when forwardly rotated, and that draws the operating oil through the second port and discharges the operating oil through the first port when reversely rotated;   a first oil passageway that provides communication between the first port of the oil pump and an oil strainer;   a second oil passageway that provides communication between the second port of the oil pump and an oil feeding passageway;   a third oil passageway that interconnects the first oil passageway and the second oil passageway and that is in parallel with the oil pump;   a first check valve that is disposed in a portion of the first oil passageway between the oil strainer and a connecting point between the first oil passageway and the third oil passageway, and that allows the operating oil to flow from a side of the oil strainer to a side of the oil pump, and that blocks the operating oil from flowing from the side of the oil pump to the side of the oil strainer;   a second check valve that is disposed in a portion of the second oil passageway between the oil feeding passageway and a connecting point between the second oil passageway and the third oil passageway, and that allows the operating oil to flow from the second oil passageway to a side of the oil feeding passageway, and that blocks the operating oil from flowing from the oil feeding passageway to a side of the second oil passageway; and   a third check valve that is disposed in the third oil passageway, and that allows the operating oil to flow from the first oil passageway to a side of the second oil passageway, and that blocks the operating oil from flowing from the second oil passageway to a side of the first oil passageway.   
     
     
         2 . The hydraulic control circuit according to  claim 1 , wherein
 an oil cooler is disposed on a portion of the second oil passageway between the oil pump and the connecting point between the second oil passageway and the third oil passageway.   
     
     
         3 . The hydraulic control circuit according to  claim 1 , wherein
 direction of rotation of the oil pump is switched according to state of travel of the vehicle.   
     
     
         4 . The hydraulic control circuit according to  claim 3 , wherein
 the oil pump is driven by an electric motor, and the electric motor is used also as a drive source of the vehicular power transmission apparatus.   
     
     
         5 . The hydraulic control circuit according to  claim 3 , wherein
 the oil pump is linked to an output shaft of a transmission capable of switching between a forward travel and a reverse travel so that power is transferrable at least from the output shaft to the oil pump.